







Running in opposite directions around a circular track 
20200511 

From Alessandra: 2. Alan and Brian are two runners. Alan runs at 6.6 m/s and Brian runs at 8.4 m/s. They start from
the same place on a circular 400 m track and run in opposite directions round and round the
track.
(a) How far has Brian run when they pass each other for the first time?
(b) After they pass each other for the second time, how much further does Brian need to run
in order to complete two laps (800 m)? Answered by Penny Nom. 





A rectangular prism with rounded corners 
20180425 

From Jackie: Rectangular prism that is 40 by 20 with rounded corners with a radius of 2.5.
What would the surface area be? Answered by Penny Nom. 





A square peg in a round hole 
20170529 

From bill: bill wants to put a 2 foot square peg into a round hole What must be the circumference of the hole? Answered by Penny Nom. 





Why does 10x10x10 give 1,000.0000000000001? 
20170412 

From Randolph: Hi, On your calculator I found that a box 10 by 10 by 10 inches has a volume of 1,000.0000000000001 cubic inches. Can you explain the numeral 1 thirteen places past the decimal? Thanks, Randy Answered by Penny Nom. 





Can you construct a regular 21gon? 
20160308 

From Peter: hi, i know that if i use a compass to draw a circle, i can use the same setting to mark 6 intervals along the circle circumference, how would i go about marking out 21 equally spaced points around the circumference?
if there an online calculator i can us, or some other interesting trick?
tia
peter Answered by Robert Dawson. 





Prove the earth is round 
20160130 

From Kevin: Working on a project for a science fair.
To prove the earth is round without the ability to get way above the surface.
How could we set up and experiment to see the curve.
My thought is using a telescope at the beach?
Form what we see so far the curve is 8 inches per mile?
So thought is set up a telescope and a target 1 mile away? Answered by Robert Dawson and Chris Fisher. 





The surface area of a round bar 
20150606 

From chirag: Please tell me the formula for finding round bar surface in square inches/ mm Answered by Penny Nom. 





A string wrapped around three circles 
20131019 

From Jim: A recent puzzle ' find the length of a string around 3 touching
1 meter diameter circles ' gave this answer : the string
touches 120° (or pi/3 meters) of each circle. Then
3(1+pi/3) = 3+pi meters is the required length. I do not see how
it was determined that the string touches 120° or pi/3 meters?
Please explain . Thankyou , Jim Answered by Penny Nom. 





6 golfers in threesomes over 7 rounds 
20130924 

From David: I have 6 golfers, (2 threesomes) who will be playing 7 rounds of golf. What is the best way to pair the 6 players so they play with as many different players over the 7 rounds? Answered by Victoria West. 





8 golfers, 3 rounds 
20130415 

From justin: I have 8 golfers going on a trip. We have 3 rounds to play.
We would like to play with everyone (with or against.) Is this
possible? If so could you send me the formula please and thank you! Answered by Robert Dawson. 





Milling round stock to square stock 
20121217 

From Bryan: Question from Bryan:
I want to know what the smallest diameter round is that will make a 31/4" square? Is there a formula for that? I am milling round stock into square.
Thank you. Answered by Harley Weston. 





The volume of a round tube 
20120207 

From I.C: I need to find out how long a 10" round tube needs to be in order for there to be .95 cubic feet of air space Answered by Harley Weston. 





Rounding 
20111214 

From seth: A decimal number rounded changed to 23.7 after it was rounded.
Give a decimal number that is less than 23.7 and another that is greater than 23.7 that each round to 23.7.
Explain to what place each number was rounded. Answered by Penny Nom. 





16 golfers and 8 rounds 
20110526 

From Gerry: 16 golfers and 8 rounds. To have each player play with as many others as possible. Answered by Victoria West. 





The nearest one and a half and the nearest inch 
20110202 

From Miranda: REASON:sarah gave the same answer when asked to round 4 seven eighth inches to the nearest one and a half and the nearest inch. explain why sarah is correct? Answered by Penny Nom. 





A rectangle with rounded corners 
20101021 

From Connie: How do you find surface area if the rectangle is 100ft. by 200ft. with quarter circles in the corners with a radius of 20ft. ? Answered by Penny Nom. 





An 18ft round pool 
20100719 

From christine: will an 18ft round pool fit on a 12x16 ft rectangular cement slab? Answered by Tyler Wood. 





3 equidistant points on a circle 
20100621 

From Brian: We have to line up 3 pins on a lifting bridle to be 120 degrees apart from each other to connect into a lifting assembly.
I know pi*d. I know straight lines connecting these points to each other will result in an equilateral triangle.
How does one find these points without using a protractor? There must be a formula (formulae) to work this out mathematically.
r = 10.5 inches
pi*d = 65.9736
3 segments( arcs) = 21.9912 which is the distance along the circumference that the points are from each other. Answered by Penny Nom. 





15 golfers 3 rounds fivesomes 
20091223 

From Dewey: I have 15 golfers playing 3 rounds of golf. We will be playing in fivesomes. Any formula that has everyone playing with a different person each round?
Thank you.
Dewey Answered by Robert Dawson. 





Greatest Number in Rounding Off 
20090625 

From paucath: what is the greatest number that can be rounded of to 4000 Answered by Janice Cotcher. 





A 4 digit number 
20090412 

From kaylin: When a 4 digit rounded to the nearest thousand,it rounds up to 3000. the hundred digit is less than 6. the digits in the ten and ones place add to a sum of 8 and they are the same . what is the number Answered by Robert Dawson and Penny Nom. 





A three digit number 
20090120 

From marcha: when this three digit number is rounded to the nearest ten, the sum of its digits
is 16 the hundreds digit of this number is 8 and the ones digit is 5, what is the number? Answered by Robert Dawson. 





Compatible numbers 
20081002 

From jeff: what exactly are compatible numbers,
math problem is:
Estimate the total weight of 2 boxes that weigh 9.4 pounds and 62,6 pounds
using rounding and compatible numbers. Which estimate is closer to the actual weight and why? Answered by Harley Weston. 





Rectangular cards on a round table 
20080611 

From Susan: How many 4" X 3.5" wide escort cards will fit on a 48" diameter table. These are for my daughters wedding. I have already added the extra spacing between the cards into the size of the cards.Thanks for your help Answered by Janice Cotcher and Harley Weston. 





Rounding 
20080509 

From wendell: write a three digit number that when rounded to the nearest ten and the nearest hundred, the answers are the same Answered by Penny Nom. 





Rounding 
20071105 

From Charles: I have been asked to explain why rounding to 3 decimal places
has become the adopted industry standard in mathematics for
showing measurement calculations. I understand that it makes
sense to round financial calculations to 2 d.p. because then it's
rounded to the nearest penny (or cent) but why would the standard
in measurement be 3? Answered by Stephen La Rocque. 





Dirt in a sloped round hole 
20070803 

From Ken: How much dirt do I need to fill a ground hole 20 ft in dia. with a sloping floor that has a ht. of 5" on one side and 12" on the other side? Answered by Stephen La Rocque. 





The size of a lot 
20070613 

From Larry: This is driving me crazy, I know i learned this in college but that was so many years ago haha. I am trying to determine how many acres
my property is. Unfortunately everywhere i look is like another language to me when seeing these formulas. My property is square shaped
so starting from one side and just working around the dimensions are: 114 feet x 95.88 feet x 100 feet x 91.91 feet. Answered by Penny Nom. 





Percentage increase and decrease 
20070613 

From Anna: I just want to if the following formula is used for the computation of a PERCENTAGE DECREASE:
Old Value  New Value/ Old Value x 100%
My immediate superior is under the impression that the said formula works ONLY for the computation of a percentage INCREASE. He believes that the formula for a percentage DECREASE:
Old Value  New Value/ NEW Value x 100%
On this score, I want to know the correct formula for the computation of percentage decrease. Thank you so much.
Answered by Penny Nom. 





A 5 digit key 
20070531 

From Michael: I have a 5 digit key pad lock on my truck.
I want to print out all of the combinations to try.
pad one=0 pad two =1 pad three=2 pad four=3 pad five =4.
can you help me find and print all combinations? Answered by Harley Weston. 





Water tank volume 
20070529 

From Cecelia: I HAVE A SEMI CIRCULAR TANK AGAINST A WALL MEASURING 6'10" ACROSS THE WIDEST PART AND 3' FROM THE WALL TO THE FRONT OF THE TANK. THE DEPTH IS 14". PLEASE HELP ME TO CALCULATE THE VOLUME OF WATER IN THE TANK. Answered by Stephen La Rocque. 





Rounding off 
20070415 

From deepak: find the smallest and the greatest numbers which when rounded off to the nearest thousand, become 6000. Answered by Stephen La Rocque. 





Angular speed 
20061004 

From Jack: A horse on a merrygoround is 7m from the center and travels at a speed of 10km/h. What is its angular speed? Answered by Stephen La Rocque. 





Estimating products by rounding 
20060924 

From Ann: my son is in the fifth grade and they are doing estimate products rounding both factors, he knows how to round off a decimal, but he is having a problem doing a decimal and a whole number for example 5.96x3=? He knows the 5.96 round off to 6. but what does the 3 round off to? Answered by Penny Nom. 





An aircraft going from city A to city B 
20060510 

From Preston: An aircraft going from city A to city B on a bearing of S69 degrees East is traveling at a speed of 430 mph. The wind is blowing out of the north to south at a speed of 25 mph. Find the ground speed and the plane's true bearing. Answered by Stephen La Rocque. 





Round to the nearest tenth 
20060506 

From Lisa: how to round a decimal fraction to the nearest tenth Answered by Penny Nom. 





How do you round off 89,100? 
20060419 

From Jeannie: My home work says to round each number to the place of the underlined digit. It has 89,100. The underlined number is 9. What do I do? Answered by Stephen La Rocque. 





Find the ground speed and the planes true heading. 
20060205 

From Jimmie: An aircraft going from city A to city B on a bearing of S69E (degrees) is traveling at a speed of 430 mph. The wind is blowing out of the north to south at a speed of 25 mph. Find the ground speed and the planes true heading. Answered by Penny Nom. 





how do i round up 9.6 to the nears ones 
20050809 

From Carlos: how do i round up 9.6 to the nears ones Answered by Penny Nom. 





Round to hundredths 
20021119 

From Brittany: Can u tell me how to do a problem like this:
35 divded by 4.8= Round to hundreths. Answered by Penny Nom. 





Rounding 27.27 
20021103 

From A parent: If you have a problem 27.27 and you need to round to the first 7 the answer would be 27 Would 27.0 be acceptable as well or is it completely wrong. Answered by Penny Nom. 





Multiplication of fractions 
20010108 

From Angela: Questions:
1. represent multiplication of fractions via an area model 2. describe why, not just how, to round decimals Answered by Penny Nom. 





Rounding 
20000914 

From MaryAnn: How many whole numbers rounded to the hundreds place, round to 400? Can you also explain why? Answered by Penny Nom. 





Rounding 
20000415 

From Tawana Brown: I was uncertain as to whether a number such as 85.25 rounding to the nearest tenth would be 85.3 or 85.2. I thought I had heard somewhere that if 5 is the last number that you don't round up. But I have also heard that anything 5 and above you do round up. It's been awhile since I've done rounding, so I need a refresher course. Answered by Walter Whiteley and Harley Weston. 





Spreading a rumor 
19990913 

From Bornstar14: There is someone who wants to spread a rumor within 7 days to 250,000,000 people. he wants to know how many people he should tell on the first day (assuming the rumor is passed by everyone who was told to the same amount of people) so that everyone knows on the 7th day. What I did is the 7th root of 250,000,000. this answer is not possible unless rounded. is it okay for the number to be approximate? Answered by Penny Nom. 





Intersecting Lines. 
19980210 

From Erik Heppler: My typewriter frequently makes mistakes. Suppose I gave you the following system of equations to solve: 35.26X + 14.95Y = 28.35 187.3X + 79.43Y = 83.29 When I looked back, I realized that I meant to use 14.96 as the "Y" coefficient in the first equation instead of 14.95. Solving the system using 14.95 and then solving another system using 14.96 with all other values the same both times results in the intersection points (1776, 4186) and (770, 1816) respectively. How can that be? Answered by Penny nom. 

